package twoSum1;

import java.util.HashMap;
import java.util.Map;

public class TowSum {
    public static void main(String[] args) {
        TowSum towSum = new TowSum();
        int [] nums = new int[]{2,7,11,15};
        int target = 9;
        int[] ints = towSum.twoSum2(nums, target);

        for (int i : ints) {
            System.out.println(i);
        }
    }

    public int[] twoSum(int[] nums, int target) {

        int n = nums.length;
        for (int i = 0; i < n; i++) {
            for (int j = i+1; j < n; j++) {
                if(nums[i]+nums[j] == target){
                    return new int[] {i,j};
                }
            }
        }
        return null;
    }


    public int[] twoSum2(int[] nums, int target) {

        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {

            if (map.containsKey(target - nums[i])) {
                return new int[]{map.get(target - nums[i]), i};
            }

            map.put(nums[i], i);

        }
        return null;
    }

}
